Many kinds of polymer compositions have been used in the field of medical supplies. These compositions have not always exhibited anti-thrombogenic characteristics when used in prosthetic and therapeutic apparatuses for handling or being in contact with blood or blood components under conditions where clotting would tend to occur, such as artificial blood vessels, catheters, artificial hearts, and artificial kidneys.
When blood is brought in contact with metal, glass, plastic or other similar surfaces, it tends to clot in a short time unless certain precautions are taken. One common precaution currently in widespread use is the treatment of the surface with heparin or with heparin reacted with quaternary ammonium compounds. Such heparin compounds are known to have anti-coagulant effects when in contact with blood. The presence of the aforementioned heparin compounds on the surface imparts anti-thrombogenic characteristics. However, previously known heparinization or compositions have not been adequate because of the short time of anti-thrombogenic activity, at most a few days in vivo (I. S. Hersch, et al, J. Biomed., Mater. Res. Symposium I, 99-104 (1971); K. Amplatz, "A simple Non-Thrombogenic Coating", Invest. Radiology, July, August, 1971, Vol. 6 or because the anti-thrombogenic characteristic was reduced to a very low level in order to make it resistant to removal by reacting it with quaternary ammonium polymers (U.S. Pat. No. 3,844,989).
It is therefore, an object of the present invention to provide novel anti-thrombogenic polymer/heparin compound compositions or mixtures which prevent blood clotting for a relatively long period of time (over one month), and which have the same high degree of anti-thrombogenic characteristics as the non-polymerized heparin-quaternary ammonium compounds, and thus provide excellent properties for use as medical materials for coatings on artificial blood vessels, catheters, artificial hearts, artificial kidneys, etc.
Another object of the present invention is to provide novel anti-microbial surfaces which contain antibiotic agents which are entrained in the surface in such a way as to be gradually released in vivo to provide effective anti-microbial action over a longer time than was previously possible when using these agents. Typical agents useful in this embodiment of the invention include penicillins, cephalosporins, etc.